There are few options for selling various aspects of your body:
1. Selling Blood Plasma - There are hundreds of for-profit plasma collection agencies in North America. Plasma collection services generally pay plasma donors between $15 and $50 per donation. Some of these services allow donations up to twice a week.
How to find someone to pay for plasma: Do a Google search for "paid plasma yourcity " or similar. You can also look in the yellow pages under "blood".
Note: each state and country has its own regulations for blood plasma donations. For instance, California does not allow payment for plasma. This option is not available for Canadians, either.
You can also check BioLife's website to find a plasma center near you.
2. Sell Blood Marrow or White Blood Cells - A healthy individual can also sell their bone marrow and/or white blood cells in many states and countries. Bone marrow or white blood cells can fetch up a few hundred dollars for donors. Again search for "sell bone marrow yourlocation " to find available options.
3. Males: Sell your sperm - Sperm banks screen generally screen their donors extensively before offering them a paid gig. But, if you do have what it takes in their eyes -- you could make an easy $50 - $250 for a few minutes of work.
4. Females: Sell your Eggs - The screening process for donated eggs is longer and more complicated than a dude trying to selling his sperm. It is also worth a lot more money. We are talking thousands to $10,000 or more for egg donators. Wow. Search google for "paid egg donation" to find more info.
5. Have Long Hair? Sell it! - Healthy long un-treated human hair can fetch up to a few thousand dollars. Even just 12 inches of un-treated hair can bring in a few hundred bucks. There are a few websites around that help hair buyers find hair sellers including: BuyandSellHair. com and HairWork. com - have a look at those links for an idea of how much hair is selling for.
6. Clinical Trials (Get paid to be a human guinea pig) - If you don't mind subjecting your body to chemicals with unknown consequences, you could get paid to participate in some sort of clinical trial. There are always new medications and experimental therapies that need to be tested. Depending on the type and length of research, you could expect anywhere from $50 - a few thousand dollars in compensation.
Paid clinical trials are available all over the world.
Where to find info about paid clinical trials / health research: A Google search for "paid clinical trials" or "paid clinical trial yourlocation" should get you started.
7. Donating Organs for Money - This is illegal in the US, Canada and many other countries. Kidneys and livers can sell for well over $10,000 (sometimes over $100,000). But, I seriously don't recommend you even consider this an option. There are plenty of good reasons why this is illegal in most countries.